U.S. patent number 11,009,781 [Application Number 16/363,628] was granted by the patent office on 2021-05-18 for display system, control device, control method, non-transitory computer-readable medium, and movable object.
This patent grant is currently assigned to PANASONIC INTELLECTUAL PROPERTY MANAGEMENT CO., LTD.. The grantee listed for this patent is PANASONIC INTELLECTUAL PROPERTY MANAGEMENT CO., LTD.. Invention is credited to Satoshi Kuzuhara, Yusuke Nihei, Hiroaki Okayama, Koji Taniguchi.
![](/patent/grant/11009781/US11009781-20210518-D00000.png)
![](/patent/grant/11009781/US11009781-20210518-D00001.png)
![](/patent/grant/11009781/US11009781-20210518-D00002.png)
![](/patent/grant/11009781/US11009781-20210518-D00003.png)
![](/patent/grant/11009781/US11009781-20210518-D00004.png)
![](/patent/grant/11009781/US11009781-20210518-D00005.png)
![](/patent/grant/11009781/US11009781-20210518-D00006.png)
![](/patent/grant/11009781/US11009781-20210518-D00007.png)
United States Patent |
11,009,781 |
Taniguchi , et al. |
May 18, 2021 |
Display system, control device, control method, non-transitory
computer-readable medium, and movable object
Abstract
A display system includes an image producing unit, a projection
unit and an adjustment unit. The image producing unit has a display
surface, and is configured to produce an image on the display
surface. The projection unit is configured to project a virtual
image to a target space with an output light of the image producing
unit. The virtual image corresponds to the image produced by the
image producing unit. The display system is configured to change a
visual distance between an eye-box and the virtual image. The
adjustment unit is configured to adjust brightness of the virtual
image according to the visual distance.
Inventors: |
Taniguchi; Koji (Fukuoka,
JP), Okayama; Hiroaki (Nara, JP), Kuzuhara;
Satoshi (Osaka, JP), Nihei; Yusuke (Kanagawa,
JP) |
Applicant: |
Name |
City |
State |
Country |
Type |
PANASONIC INTELLECTUAL PROPERTY MANAGEMENT CO., LTD. |
Osaka |
N/A |
JP |
|
|
Assignee: |
PANASONIC INTELLECTUAL PROPERTY
MANAGEMENT CO., LTD. (Osaka, JP)
|
Family
ID: |
1000005560218 |
Appl.
No.: |
16/363,628 |
Filed: |
March 25, 2019 |
Prior Publication Data
|
|
|
|
Document
Identifier |
Publication Date |
|
US 20190302583 A1 |
Oct 3, 2019 |
|
Foreign Application Priority Data
|
|
|
|
|
Mar 29, 2018 [JP] |
|
|
JP2018-063909 |
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G02B
27/0179 (20130101); G03B 21/28 (20130101); G02F
1/133602 (20130101); H04N 9/77 (20130101); G06F
9/3004 (20130101); G03B 21/145 (20130101); G03B
21/142 (20130101); G02B 27/0101 (20130101); G02B
2027/0185 (20130101) |
Current International
Class: |
G03B
21/14 (20060101); G02B 27/01 (20060101); H04N
9/77 (20060101); G06F 9/30 (20180101); G02F
1/1335 (20060101); G03B 21/28 (20060101); G02F
1/13357 (20060101) |
Field of
Search: |
;353/20 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
|
|
|
|
|
|
|
H03-88928 |
|
Sep 1991 |
|
JP |
|
06-087043 |
|
Dec 1994 |
|
JP |
|
H11-119147 |
|
Apr 1999 |
|
JP |
|
2014-142438 |
|
Aug 2014 |
|
JP |
|
2015-043012 |
|
Mar 2015 |
|
JP |
|
2017-21302 |
|
Jan 2017 |
|
JP |
|
Other References
Notice of Refusal dated Oct. 23, 2019 issued in Japanese Patent
Application No. 2018-063909 along with English translation. cited
by applicant.
|
Primary Examiner: Dowling; William C.
Attorney, Agent or Firm: Greenblum & Bernstein,
P.L.C.
Claims
The invention claimed is:
1. A display system, comprising: an image producing unit having a
display surface, and configured to produce an image on the display
surface; a projection unit configured to project a virtual image to
a target space with an output light of the image producing unit,
the projection unit including a zoom lens, the virtual image
corresponding to the image produced by the image producing unit,
and the display system being configured to change a visual distance
between an eye-box and the virtual image, wherein even when the
visual distance is changed by changing a position of the zoom lens,
a size of the image displayed on the image producing unit is
changed so that a display field angle of the virtual image
projected by the projection unit is constant, regardless of a
change in the visual distance; and an adjustment unit configured to
adjust brightness of the virtual image according to the visual
distance so that the brightness of the virtual image fall within a
prescribed target range, when the size of the image is changed so
that the display field angle of the virtual image is constant
according to the visual distance being changed by changing the
position of the zoom lens.
2. The display system of claim 1, wherein the adjustment unit is
further configured to adjust the brightness of the virtual image
according to an ambient light illuminance.
3. The display system of claim 1, wherein the adjustment unit is
configured to change a luminance of the display surface to adjust
the brightness of the virtual image.
4. The display system of claim 2, wherein the adjustment unit is
configured to change a luminance of the display surface to adjust
the brightness of the virtual image.
5. The display system of claim 1, wherein the adjustment unit is
configured to change lightness of colors of contents in the image
produced by the image producing unit to adjust the brightness of
the virtual image.
6. The display system of claim 2, wherein the adjustment unit is
configured to change lightness of colors of contents in the image
produced by the image producing unit to adjust the brightness of
the virtual image.
7. The display system of claim 3, wherein the adjustment unit is
configured to change lightness of colors of contents in the image
produced by the image producing unit to adjust the brightness of
the virtual image.
8. The display system of claim 4, wherein the adjustment unit is
configured to change lightness of colors of contents in the image
produced by the image producing unit to adjust the brightness of
the virtual image.
9. The display system of claim 1, wherein the adjustment unit is
configured to increase the brightness of the virtual image, as the
visual distance is increased.
10. The display system of claim 1, wherein the eye-box is a space
region where eyes of an observer that observes the virtual image
are located.
11. The display system of claim 1, wherein the display system is
applied to a movable object, and the target space is a space in
front of a windshield of the movable object.
12. The display system of claim 1, wherein the adjustment unit is
configured to change display information of contents in the image
produced by the image producing unit to adjust the brightness of
the virtual image.
13. The display system of claim 1, wherein the image producing unit
includes: a liquid crystal panel, a front face of which constitutes
the display surface; and a light source device serving as a
backlight for the liquid crystal panel.
14. A control device, comprising the adjustment unit to be used for
the display system of claim 1, the control device is provided
separately from a display device including the image producing unit
and the projection unit.
15. A movable object comprising: the display system of claim 1; and
a reflective member configured to reflect light emitted from the
projection unit.
16. The display system of claim 1, wherein the adjustment unit is
configured to change lightness of colors of contents in the image
produced by the image producing unit according to the contents to
adjust the brightness of the virtual image.
17. The display system of claim 16, wherein the contents include a
first content and a second content, and the adjustment unit changes
lightness of colors only for content whose visual distance is
changed.
18. A control method for a display system, the display system
comprising: an image producing unit having a display surface, and
configured to produce an image on the display surface; and a
projection unit configured to project a virtual image to a target
space with an output light of the image producing unit, the
projection unit including a zoom lens, the virtual image
corresponding to the image produced by the image producing unit,
and the display system being configured to change a visual distance
between an eye-box and the virtual image, wherein even when the
visual distance is changed by changing a position of the zoom lens,
a size of the image displayed on the image producing unit is
changed so that a display field angle of the virtual image
projected by the projection unit is constant, regardless of a
change in the visual distance, the control method comprising
adjusting brightness of the virtual image according to the visual
distance so that the brightness of the virtual image fall within a
prescribed target range, when the size of the image is changed so
that the display field angle of the virtual image is constant
according to the visual distance being changed by changing the
position of the zoom lens.
19. A non-transitory computer-readable medium having stored thereon
a computer program which, upon execution by a computing system,
causes the computing system to perform a control method for a
display system, the display system comprising: an image producing
unit having a display surface, and configured to produce an image
on the display surface; and a projection unit configured to project
a virtual image to a target space with an output light of the image
producing unit, the projection unit including a zoom lens, the
virtual image corresponding to the image produced by the image
producing unit, and the display system being configured to change a
visual distance between an eye-box and the virtual image, wherein
even when the visual distance is changed by changing a position of
the zoom lens, a size of the image displayed on the image producing
unit is changed so that a display field angle of the virtual image
projected by the projection unit is constant, regardless of a
change in the visual distance, the control method comprising
adjusting brightness of the virtual image according to the visual
distance so that the brightness of the virtual image fall within a
prescribed target range, when the size of the image is changed so
that the display field angle of the virtual image is constant
according to the visual distance being changed by changing the
position of the zoom lens.
Description
CROSS-REFERENCE TO RELATED APPLICATION
This application is based upon and claims the benefit of priority
of Japanese Patent Application No. 2018-063909, filed on Mar. 29,
2018.
TECHNICAL FIELD
This disclosure relates generally to a display system, a control
device, a control method, a non-transitory computer-readable
medium, and a movable object, and more particularly relates to a
display system configured or designed to project a virtual image, a
control device with an adjustment unit to be used for the display
system, a control method for the display system, a non-transitory
computer-readable medium, and a movable object with the display
system.
BACKGROUND ART
A document 1 (JPH06-87043 U) discloses a display device for
vehicle. This display device for vehicle is configured to project a
display image onto a windbreak glass with a combiner. The display
device for vehicle is disposed below the windbreak glass, and
includes a light emission display means having a light source, a
lens that is a collimator, and a transmissive display body. The
display device for vehicle moves, based on a vehicle speed, the
light emission display means (e.g., the lens) forward or backward
in a direction in which the light is emitted toward the combiner to
change an image forming position of a virtual image to be
displayed. The display device for vehicle therefore can change a
visual distance between the virtual image and an observer (an
eye-box) that observes the virtual image.
In case where a luminance of the light source is constant, if to
change the visual distance the lens is merely moved forward or
backward as the display device for vehicle disclosed by the
document 1, the observer observing the virtual image may feel
uncomfortable as if the luminance of the virtual image has changed.
Thus, the display quality of the virtual image may be reduced and
the visibility of the virtual image may be also reduced.
SUMMARY
The present disclosure is directed to a display system, a control
device, a control method, a non-transitory computer-readable
medium, and a movable object, which can suppress a reduction in
display quality and visibility of a virtual image.
A display system according to an aspect of the present disclosure
includes an image producing unit, a projection unit and an
adjustment unit. The image producing unit has a display surface and
is configured to produce an image on the display surface. The
projection unit is configured to project a virtual image to a
target space with an output light of the image producing unit. The
virtual image corresponds to the image produced by the image
producing unit. The display system is configured to change a visual
distance between an eye-box and the virtual image. The adjustment
unit is configured to adjust brightness of the virtual image
according to the visual distance.
A control device according to an aspect of the present disclosure
includes the adjustment unit to be used for the above-mentioned
display system. The control device is provided separately from a
display device including the image producing unit and the
projection unit.
A control method according to an aspect of the present disclosure
is a control method for a display system. The display system
includes an image producing unit and a projection unit. The image
producing unit has a display surface, and configured to produce an
image on the display surface. The projection unit is configured to
project a virtual image to a target space with an output light of
the image producing unit. The virtual image corresponds to the
image produced by the image producing unit. The display system is
configured to change a visual distance between an eye-box and the
virtual image. The control method includes adjusting brightness of
the virtual image according to the visual distance.
A non-transitory computer-readable medium according to an aspect of
the present disclosure has stored thereon a computer program which,
upon execution by a computing system, causes the computing system
to perform a control method for a display system. The display
system includes: an image producing unit having a display surface,
and configured to produce an image on the display surface; and a
projection unit configured to project a virtual image to a target
space with an output light of the image producing unit. The virtual
image corresponds to the image produced by the image producing
unit. The display system is configured to change a visual distance
between an eye-box and the virtual image. The control method
includes adjusting brightness of the virtual image according to the
visual distance.
A movable object according to an aspect of the present disclosure
includes: the above-mentioned display system; and a reflective
member configured to reflect light emitted from the projection
unit.
BRIEF DESCRIPTION OF THE DRAWINGS
The figures depict one or more implementations in accordance with
the present disclosure, by way of example only, not by way of
limitations. In the figures, like reference numerals refer to the
same or similar elements.
FIG. 1 is a schematic block drawing of a display system according
to an exemplary embodiment.
FIG. 2 is a schematic drawing of a movable object (automobile) with
the display system.
FIG. 3 is a schematic drawing showing a visual field of eyes of a
user driving the movable object.
FIG. 4A is a drawing showing appearance of a virtual image in case
of not adjusting a size of an image when changing a visual distance
in the display system.
FIG. 4B is a drawing showing appearance of the virtual image in
case of adjusting the size of the image when changing the visual
distance in the display system.
FIG. 5 is a flowchart for explaining operation of an adjustment
unit of the display system.
FIG. 6 is a schematic block drawing of a Third Variation of the
display system.
FIG. 7 is a schematic block drawing of a display system with a
control device according to an exemplary embodiment.
DETAILED DESCRIPTION
(1) Overview
An exemplary embodiment described below is merely one of various
embodiments according to the present disclosure. The exemplary
embodiment described below may be made various modifications based
on designs or the like, as long as the object of the present
disclosure can be achieved. Also since FIGS. 1 to 7 explained in
the exemplary embodiment described below are schematic drawings,
the ratios of sizes of elements shown in FIGS. 1 to 7 do not
necessarily reflect ratios of real sizes thereof.
A display system 1 of the present embodiment, as shown in FIG. 1,
includes an image producing unit 2 and a projection unit 3. The
image producing unit 2 has a display surface 210 and is configured
to produce an image 7 (refer to FIG. 4B) on the display surface
210. The projection unit 3 is configured to project (form) a
virtual image 300 to a target space 400 with an output light of the
image producing unit 2. The virtual image 300 corresponds to the
image 7 produced by the image producing unit 2. The "target space"
mentioned herein is for example assumed to be a space including a
region for forming the image of the display system 1.
As shown in FIGS. 1 to 3, the display system 1 is assumed to be a
Head-Up Display (HUD) to be used for an automobile 100 as a movable
object. Accordingly, the target space 400 is a space outside the
automobile 100 and mainly corresponds to a space in front of a
windshield 101 (reflective member) of the automobile 100.
However the display system 1 is not necessarily applied to the
Head-Up Display for the automobile 100, but may be also applied to
the Head-Up Display for movable objects (such as a two-wheel
vehicle, a train, an aircraft, a construction machine and a ship)
other than the automobile 100. Alternatively the display system 1
is not limited to the Head-Up Display, but may be applied to an
Augmented Reality (AR) display device that superimposes information
on the real world.
As shown in FIG. 1, the display system 1 is configured to change a
visual distance L0 (visual range) between an eye-box 800 and the
virtual image 300. The eye-box 800 is a space region where eyes of
an observer (user 200) that observes the virtual image 300 would be
located.
Herein the display system 1 of the present embodiment further
includes an adjustment unit 50 (refer to FIG. 1) configured to
adjust brightness of the virtual image 300 according to the visual
distance L0. As one example, the adjustment unit 50 is configured
to change a luminance of the display surface 210 to adjust the
brightness of the virtual image 300. The brightness of the virtual
image 300 may be however adjusted by changing lightness of colors
of contents in the image 7 (refer to a First Variation described
later).
According to the present disclosure, in case where the visual
distance L0 is changed, it is possible to more reduce a possibility
that the observer (user 200) feels uncomfortable as if the
luminance of the virtual image 300 has changed, compared with the
case of the above Document 1 where the display device for vehicle
merely moves the lens forward or backward. Thus, the present
disclosure can suppress a reduction in display quality and
visibility of the virtual image 300.
(2) Details
(2.1) Whole Configuration
Hereinafter, the display system 1 of the present embodiment will be
described in detail with reference to FIGS. 1 to 5. As shown in
FIG. 1, the display system 1 includes a display device 4 and is
applied to as one example the automobile 100 that is a movable
object, as explained in the column of the above "(1) Overview". The
display device 4 is the Head-Up Display to be used for the
automobile 100, as one example.
Also hereinafter, as one example, the adjustment unit 50 explained
in the column of the above "(1) Overview" is assumed to be provided
in a controller 5 of the display device 4.
(2.2) Display Device
The display device 4 is disposed inside a vehicle cabin of the
automobile 100 to project the image 7 (refer to FIG. 4B) to the
windshield 101 of the automobile 100 from the downside. In the
example of FIG. 2, the display device 4 is placed in a dashboard
102 below the windshield 101. As shown in FIG. 1, the display
device 4 includes the image producing unit 2, the projection unit
(optical system) 3, the controller 5, a drive unit 6 and a detector
X1.
The image producing unit 2 is configured to output light to form
the image 7. In the present embodiment, as one example, the image
producing unit 2 includes a liquid crystal panel 21 (Liquid Crystal
Display: LCD) and a light source device 22, as shown in FIG. 1. The
liquid crystal panel 21 has in a front face thereof the display
surface 210, and forms the image 7 on the display surface 210. The
liquid crystal panel 21 is disposed in front of the light source
device 22. The light source device 22 is used as a backlight for
the liquid crystal panel 21. The light source device 22 is a
so-called plane light source. The light source device 22 is a
side-light type light source device with a solid-state light
emitting element such as a light emitting diode or a laser diode.
The light emitted by the light source device 22 passes through the
liquid crystal panel 21 and is output from the image producing unit
2.
In the image producing unit 2, when the light source device 22
emits light while the image 7 is displayed on the liquid crystal
panel 21, the light emitted forward by the light source device 22
passes through the liquid crystal panel 21, and is output forward
from the front face of the liquid crystal panel 21. In this case,
since the light output forward from the front face of the liquid
crystal panel 21 is light that has reflected the image 7 displayed
on the liquid crystal panel 21, it results in that light forming
the image 7 is output as an "output light" from the image producing
unit 2.
Herein a longitudinal direction of the liquid crystal panel 21
corresponds to a longitudinal direction of the image 7 to be
projected, and a lateral direction of the liquid crystal panel 21
corresponds to a lateral direction of the image 7 to be projected.
The longitudinal direction of the image 7 to be projected
corresponds to a longitudinal direction of the virtual image 300
(refer to FIGS. 1 to 3) to be projected onto the target space 400,
namely a direction along a vertical direction in a visual field of
eyes of the user 200 (refer to FIG. 2). The lateral direction of
the image 7 to be projected corresponds to a lateral direction of
the virtual image 300 to be projected onto the target space 400,
namely a direction along a horizontal direction in the visual field
of eyes of the user 200.
The projection unit 3 is configured to reflect the output light of
the image producing unit 2 to project the image 7. In the present
embodiment, since the display device 4 is the Head-Up Display as
above and projects the image 7 onto the windshield 101 (refer to
FIG. 1) that is a reflective member, the projection unit 3 projects
the image 7 with respect to an object configured by the windshield
101.
In the present embodiment, as one example, the projection unit 3 as
shown in FIG. 1 includes a mirror 31 and a zoom lens 32 (lens
group). The zoom lens 32 is disposed between the display surface
210 of the liquid crystal panel 21 and the mirror 31. The zoom lens
32 includes, for example, a drive lens 321 having a light diffusing
action, and a fixed lens 322 having a light condensing action. The
projection unit 3 is configured such that the fixed lens 322, the
drive lens 321 and the mirror 31 are arranged in that order on an
optical path of light output from the display surface 210 of the
liquid crystal panel 21. Herein the zoom lens 32 is the lens group
that includes two lenses, but the number of the lenses is not
particularly limited.
The projection unit 3 firstly condenses the output light of the
image producing unit 2 with the fixed lens 322, and then diffuses
the output light with the drive lens 321 to be reflected by the
mirror 31, thereby the reflected light being output toward the
windshield 101. The mirror 31 is a concave mirror, as one example.
To make the output light of the image producing unit 2 incident
onto the mirror 31, the mirror 31 is disposed on the side opposite
to the light source device 22, of the liquid crystal panel 21,
namely, in front of the liquid crystal panel 21.
According to the configuration as above, the projection unit 3
properly modifies the size of the image 7 produced by the image
producing unit 2 and projects the modified image as a projection
image onto the windshield 101 that is an object, and the virtual
image 300 is therefore projected (formed) onto the target space
400. The "virtual image" mentioned herein means that when the light
rays output from the display device 4 are diffused by a reflective
member such as the windshield 101, the image is formed with the
diffused light rays as if a real object exists.
In the display device 4, the virtual image 300 in the target space
400 is formed onto a virtual screen 501 intersecting with an
optical axis 500 of the display device 4, as shown in FIG. 2. In
the present embodiment, the optical axis 500 is along a road
surface 600 in front of the automobile 100, in the target space 400
(in front of the automobile 100). The virtual screen 501 where the
virtual image 300 is formed is arranged substantially vertically
with respect to the road surface 600. For example, in case where
the road surface 600 is a horizontal plane, the virtual image 300
is displayed along a vertical plane.
Accordingly, the user 200 driving the automobile 100, as shown in
FIG. 3, can see the virtual image 300 projected by the display
device 4 with overlapping the virtual image 300 with a real space
spreading in front of the automobile 100. Therefore, the display
device 4 for example can display, as the virtual image 300, various
driving assist information (such as vehicle speed information,
navigation information, pedestrian information, preceding vehicle
information, lane departure warning information, and vehicle
condition information), thereby making the user 200 visually
recognize it. In the example of FIG. 3, the virtual image 300
includes a first virtual image 300A and a second virtual image
300B. Details of the first virtual image 300A (hereinafter,
referred to "contents") include an arrow (e.g., for guiding the
left-hand turn), the present location or the like. Contents of the
second virtual image 300B include the vehicle speed information,
the drawing showing "50 km/h" as one example. Accordingly, the user
200 can visually obtain the driving assist information with only
slightly shifting sight line while turning the user's eyes on the
front of the windshield 101.
The controller 5 controls the image producing unit 2 (including the
liquid crystal panel 21 and the light source device 22). Also the
controller 5 controls the drive unit 6. The controller 5 for
example includes a microcomputer mainly with a Central Processing
Unit (CPU) and a memory. In other words, the controller 5 is
realized by a computer (processor) including the CPU and the
memory, and the computer, when the CPU executes a computer program
stored in the memory, functions as the controller 5. The computer
program is for example assumed to be stored in advance in the
memory of the controller 5, but at least part of the computer
program may be provided through a telecommunication network such as
the Internet or a non-transitory storage medium such as a memory
card.
The controller 5 controls the image producing unit 2 to produce the
arbitrary image 7 on the display surface 210. That is, the
controller 5 can allow the liquid crystal panel 21 to display
(plot) arbitrary video contents by software processing, and
accordingly the arbitrary image 7 can be produced on the display
surface 210. For example upon projection of the virtual image 300
as in FIG. 3 (the first virtual image 300A and the second virtual
image 300B) onto the target space 400, the controller 5 determines
the contents of the first virtual image 300A (the arrow, the
present location or the like) and the contents of the second
virtual image 300B (the vehicle speed information). The controller
5 further determines where the image 7 should be displayed on the
front surface of the liquid crystal panel 21, namely, the display
surface 210. In short, the controller 5 can determine displaying
the image 7 corresponding to the first virtual image 300A on an
upper half region or a lower half region of the display surface
210. If the image 7 is changed a position on the display surface
210, the virtual image 300 also changes in a relative display
position, depending on the position change of the image 7.
As shown in FIG. 1, the display system 1 of the present embodiment
is configured to change the visual distance L0 between the eye-box
800 and the virtual image 300. More specifically the drive unit 6
moves an optical element included in the projection unit 3 to
change the visual distance L0. That is, the drive unit 6 is
configured to change a position of the optical element. In the
present embodiment, as one example, the drive lens 321 is a target
to be driven by the drive unit 6. Under control of the controller
5, the drive unit 6 moves the drive lens 321 to be closer to or
more separated from the fixed lens 322, thereby can increasing or
decreasing the visual distance L0 between the eye-box 800 and the
virtual image 300. The drive unit 6 may include an
electrically-driven actuator such as a motor. The drive unit 6 may
be further configured to physically change a position or a
direction of the display surface 210 of the liquid crystal panel
21, or turn the mirror 31 to change a direction thereof, although
detail explanations thereof are omitted.
If the drive lens 321 is moved in a direction of shortening an
interval between itself and the image producing unit 2, the visual
distance L0 increases. This reason is that magnification of the
zoom lens 32 becomes larger by shortening the interval. However,
only if the interval is merely shortened, a display field angle
(viewing angle) of the virtual image 300 when viewed from the user
200 also becomes larger, as shown in FIG. 4A. FIG. 4A schematically
shows, by rectangular lattice shape, the virtual image 300 when
viewed from the user 200, where a reference sign "301" represents
the virtual image 300 before the change in the visual distance L0,
and a reference sign "303" represents the virtual image 300 after
the change in the visual distance L0. That is, if the size of the
image 7 displayed on the image producing unit 2 is kept constant
between before and after the movement of the drive lens 321, the
size of the virtual image 300 visually obtained by the user 200
would be unwillingly changed. In the example of FIG. 4A, the size
of the virtual image 300 is increased.
To solve this problem, the controller 5 decreases the size of the
image 7 to be displayed on the image producing unit 2 in accordance
with the movement of the drive lens 321 in order to keep constant
the display field angle between before and after the movement of
the drive lens 321 performed for increasing the visual distance L0
(refer to FIG. 4B). FIG. 4B schematically shows, by rectangular
lattice shape, the image 7 produced on the display surface 210 of
the image producing unit 2, where a reference sign "70" represents
the image 7 before change in the size thereof, and a reference sign
"71" represents the image 7 after the change in the size thereof
(downsized). The controller 5 determines: a driving quantity of the
drive unit 6; and the size of the image 7. In this case, the
driving quantity of the drive unit 6 is for example proportional to
a variation in the size of the image 7 to be produced on the
display surface 210. In this way when the display field angle is
controlled to be constant between before and after the movement of
the drive lens 321, it is possible to suppress a possibility that
the user 200 viewing the virtual image 300 feels uncomfortable due
to the increase in the display field angle of the virtual image 300
together with the increase in the visual distance L0 for example.
Note that "constant" of "the display field angle is controlled to
be constant" mentioned herein is not necessarily "strictly
constant". The display field angle may be substantially constant
within a prescribed range including an acceptable slight error.
Herein the size of the image 7 to be displayed on the display
surface 210 of the image producing unit 2 means a size of an image
that is displayed with pixels to be used for displaying the
contents, of a plurality of pixels constituting the display surface
210.
The controller 5 of the present embodiment, as shown in FIG. 1,
includes the adjustment unit 50 that is configured to adjust
brightness of the virtual image 300 according to the change in the
visual distance L0 performed by the drive unit 6. The adjustment
unit 50 will be explained in more detail in the column of the
following "(2.3) Adjustment unit".
The detector X1 is configured to detect an ambient light
illuminance (e.g., a light illuminance in the target space 400
outside the automobile 100, the target space 400 including a region
for forming the image of the display device 4), and transmit
information on the detected light illuminance to the controller
5.
The detector X1, as shown in FIG. 1, includes an illuminance sensor
X10, an amplifier X11, an A/D converter X12 and the like. The
illuminance sensor X10 includes a photo Integrated Circuit (IC)
detecting the light illuminance of the target space 400, for
example, and is disposed near an opening 103 in the dashboard 102
of the automobile 100. The illuminance sensor X10 outputs, to the
amplifier X11, an illuminance voltage (analog signal) corresponding
to the light illuminance of the target space 400. The amplifier X11
amplifies the signal received from the illuminance sensor X10 and
outputs it to the A/D converter X12. The A/D converter X12 converts
the output signal of the amplifier X11 to a digital signal, and
transmits it, as a value of the light illuminance (detection
value), to the controller 5.
(2.3) Adjustment Unit
Hereinafter, the configuration of the adjustment unit 50 of the
controller 5 will be mainly described in more detail. Explanations
of the basic control processing regarding plotting of the video
contents in the image producing unit 2 and driving of the drive
unit 6 as described above may be appropriately omitted in this
column.
As shown in FIG. 1, the controller 5 includes the adjustment unit
50, an input unit 51, an output unit 52 and a storage unit 53. The
storage unit 53 may be the above-mentioned memory or another unit
provided separately from the above-mentioned memory.
The controller 5 performs control of changing the visual distance
L0 with the drive unit 6, by receiving an operation input from the
user 200 through an operation unit (not shown), or automatic
control in accordance with the video contents to be displayed. The
adjustment unit 50 is configured to adjust the brightness of the
virtual image 300 (i.e., execute adjustment processing) according
to the change in the visual distance L0. In this embodiment, the
adjustment unit 50 increases the brightness of the virtual image
300, as the visual distance L0 is increased. Also the adjustment
unit 50 changes a luminance of the display surface 210 to adjust
the brightness of the virtual image 300. In other words, the
controller 5 changes, in accordance with the driving quantity of
the drive unit 6, both of the size of the image 7 to be displayed
on the liquid crystal panel 21 and the optical quantity of the
light to be output from the liquid crystal panel 21.
The storage unit 53 is a data-rewritable memory, and more
preferably a nonvolatile memory. For example, the storage unit 53
stores in advance therein: first data where the driving quantities
and sizes of the image 7 are made associated with each other; and
second data where the driving quantities and the optical quantities
(target values) of the backlight (light source device 22) are made
associated with each other. The first data is preferably data in
which the driving quantity is proportional to the variation in the
size of the image 7, as mentioned above. The second data is
preferably data obtained by analyzing in advance an optical
quantity distribution relating to the light source device 22 by a
test and the like. In particular, light intensity (candela) of the
light, emitted from the light source device 22 to the display
surface 210, may have variations in some extent rather than be
completely uniform on the whole area of the display surface 210.
For example, the light intensity becomes larger, as it approaches a
central area of the display surface 210. Thus, the virtual image
300 projected may be changed in a luminance, also depending on a
display position of the image 7 on the display surface 210 (e.g.,
whether the display position is the central area, an upper area or
a lower area, of the display surface 210, or the like). For this
reason, the optical quantity distribution of the light source
device 22 with respect to the area of the display surface 210 is
one of parameters important for the adjustment processing to be
performed by the adjustment unit 50 according to the change in the
visual distance L0. Accordingly the second data preferably includes
a plurality of respective optical quantities (target values)
corresponding to a plurality of display positions (X-Y coordinate
values) of the image 7 on the display surface 210, with respect to
each driving quantity.
In particular, as described above, the controller 5 changes the
size of the image 7 to be displayed on the image producing unit 2
in accordance with the movement of the drive lens 321 in order to
keep constant the display field angle between before and after the
movement of the drive lens 321 for increasing (or decreasing) the
visual distance L0. However, when the size of the image 7 is for
example downsized, it narrows the usage area to be used for
displaying the image 7 on the display surface 210. Therefore, if,
without the adjustment unit 50, the optical quantity of the light
source device 22 is unchanged, it would result in reducing the
luminance of the virtual image 300 viewed by the user 200.
On the other hand, the adjustment unit 50 generates a control
signal based on the second data so that, even if the visual
distance L0 is changed, the luminance of the virtual image 300 is
kept substantially constant, that is, the luminance of the virtual
image 300 falls within a prescribed target range. The controller 5
outputs the control signal to the image producing unit 2 to adjust
the brightness of the virtual image 300. Accordingly, even if the
size of the image 7 is changed for keeping constant the display
field angle of the virtual image 300, the display system 1 can
suppress the virtual image 300 from being blurred and dimly seen
due to the change in the brightness of the virtual image 300 viewed
from the user 200. The display system 1 therefore can suppress a
reduction in display quality and visibility of the virtual image
300.
The adjustment unit 50 preferably controls the optical quantity of
the light source device 22 so as to be gradually increased
exponentially (as drawing a curve), rather than proportionally,
from the current optical quantity to the target value of the
optical quantity determined based on the second data.
Also the adjustment unit 50 periodically receives the detection
value from the detector X1, regardless of the presence or absence
of the change in the visual distance L0, and adjusts the luminance
of the virtual image 300 based on the detection value. For example
when the ambient light illuminance is changed due to day time or
night time, or that the automobile 100 has entered a tunnel, there
is a possibility that the visibility of the virtual image 300 may
be reduced. So, the storage unit 53 stores in advance therein data
where detection values and the optical quantities (target values)
of the light source device 22 are made associated with each other.
To prevent the reduction in the visibility, the adjustment unit 50
controls, based on the data in the storage unit 53, the light
source device 22 so that the current optical quantity substantially
matches with the target value of the optical quantity corresponding
to the detection value received from the detector X1 to adjust the
luminance of the virtual image 300. The adjustment unit 50 further
controls the light source device 22 to adjust the luminance of the
virtual image 300, when receiving a prescribed operation input from
the user 200 through the operation unit (not shown) in addition to
such the automatic luminance adjustment.
The input unit 51 is electrically connected to an output terminal
of the A/D converter X12 of the detector X1 with a signal line S11
(refer to FIG. 1). The input unit 51 is configured to periodically
receive the detection value of the light illuminance from the
detector X1.
The output unit 52 is electrically connected to the image producing
unit 2 with a signal line S12 (refer to FIG. 1). The output unit 52
is configured to output the control signal generated by the
adjustment unit 50 to the image producing unit 2. When receiving
the control signal, the image producing unit 2 allows a lighting
circuit, which performs lighting control for the light source
device 22 (light source), to change the light output level of the
light source so that the current optical quantity matches with the
optical quantity indicated in the control signal.
When changing the visual distance L0, the adjustment unit 50
preferably adjusts the brightness of the virtual image 300 also in
consideration of the detection value received from the detector X1.
For example, the second data may include respective kinds of data
tables that are set for the day time, the night time and the tunnel
or the like. The adjustment unit 50 may select a kind of data table
set for the night time, when for example determining that it is the
night time now based on the received detection value, and then
determine, with reference to the kind of data table, the optical
quantity (target value) of the light source device 22 corresponding
to the driving quantity of the drive unit 6.
The controller 5 is electrically connected to an Electronic Control
Unit (ECU) installed in the automobile 100, and configured to
transmit to and receive various electrical signals to and from the
ECU.
(2.4) Operation of Adjustment Unit
Hereinafter, operation of the adjustment unit 50 will be explained
with reference to a flowchart of FIG. 5. Herein as one example, it
is assumed that the visual distance L0 is increased from a first
distance L1 to a second distance L2, as shown in FIG. 1.
First, when determining to carry out change of the visual distance
L0, the controller 5 determines (calculates) the driving quantity
of the drive unit 6 (herein a displacement quantity of the drive
lens 321) corresponding to a difference between the first distance
L1 and the second distance L2 (Step S1). When the driving quantity
is determined, the controller 5 refers to the first data in the
storage unit 53 and determines a reduced size of the image 7
corresponding to the driving quantity (Step S2). Then the
controller 5 starts an execution of the adjustment processing by
the adjustment unit 50 (Step S3).
The adjustment unit 50 refers to the second data in the storage
unit 53 and then selects, using the last detection value received
from the detector X1, the kind of data table corresponding to the
current light illuminance (Step S4). The adjustment unit 50
determines, based on the selected kind of data table, the driving
quantity and the optical quantity (target value) of the light
source device 22 corresponding to the display position of the image
7 on the display surface 210 (Step S5).
When the displacement quantity of the drive lens 321, the size of
the image 7 and the target value of the optical quantity are
determined, the controller 5 transmits the control signal including
those information to the drive unit 6 and the image producing unit
2 (Step S6). More specifically the controller 5 controls and allows
the drive unit 6 to move the drive lens 321 closer to the fixed
lens 322 by the determined displacement quantity (refer to an arrow
in FIG. 1). Furthermore the controller 5 allows the image producing
unit 2 to reduce the size of the image 7 at the substantially same
timing as the control for the drive unit 6. In addition, the
controller 5 allows the image producing unit 2 to gradually
increase the current optical quantity to the target value, of the
light source device 22.
As a result, the virtual image 300(301) at a position separated by
the first distance L1 from the eye-box 800 is moved farther away
from the eye-box 800, thereby reaching a position separated by the
second distance L2 from the eye-box 800 (refer to the virtual image
300(302) in FIG. 1). In the present embodiment, even if the visual
distance L0 of the virtual image 300 is changed, the adjustment
unit 50 can suppress, by the adjustment processing, the reduction
in the display quality and the visibility of the virtual image
300.
(3) Variation
Next, variations of the exemplary embodiment described above will
be enumerated one after another. Hereinafter, the exemplary
embodiment described above may be referred to as a "basic example".
Optionally any of the variations below may be adopted in
combination with the above basic example and/or the other variation
as appropriate.
(3.1) First Variation
In the basic example, the adjustment unit 50 is configured to
change the luminance of the display surface 210 to adjust the
brightness of the virtual image 300. However, the adjustment unit
50 is not limited to such the configuration, but may be configured
to change lightness of colors (color tone) of the contents in the
image 7 to adjust the brightness of the virtual image 300.
Optionally the adjustment unit 50 may be configured to change
properly both of the luminance of the display surface 210 and the
lightness of colors of the contents to adjust the brightness of the
virtual image 300. The liquid crystal panel 21 may be for example
an LCD capable of displaying full colors.
More specifically the adjustment unit 50 changes the lightness of
colors in accordance with the contents included in the image 7. For
example when explained using FIG. 3, there are cases where the
display system 1 may change only the visual distance L0 of the
first virtual image 300A including the contents as the arrow
without changing the visual distance L0 of the second virtual image
300B including the contents as the vehicle speed information. It is
assumed that, while the visual distance L0 is set to the first
distance L1, the second virtual image 300B has a display color of
light gray close to white. When the visual distance L0 is changed
to the second distance L2, the adjustment unit 50 may reduce the
lightness of colors of the second virtual image 300B so as to
gradually increase a ratio of black color. Since the lightness of
colors is reduced according to the increase in the visual distance
L0, the display system 1 can suppress the first virtual image 300A
from being blurred and dimly seen.
The adjustment unit 50 may determine a target value for the
lightness of colors based on only the display color of the first
virtual image 300A, or based on a correlation with the display
color of the second virtual image 300B, which has been displayed
near the first virtual image 300A, and the visual distance L0 of
which is unchanged.
Alternatively the adjustment unit 50 may change the contents
themselves (display information) of the virtual image 300, when
changing the visual distance L0. For example, the adjustment unit
50 may display, while the visual distance L0 is set to the first
distance L1, the virtual image 300 including both contents of the
vehicle speed information and the navigation information, but, when
it is changed to the second distance L2, the virtual image 300
including only the contents of the vehicle speed information with
erasing the contents of the navigation information. In this case,
the adjustment unit 50 may also change the lightness of colors
together with the change in the contents themselves.
(3.2) Second Variation
In the basic example, when changing the visual distance L0, the
controller 5 changes the size of the image 7 to keep constant the
display field angle of the virtual image 300 between before and
after the movement of the drive lens 321. However, the controller 5
is not limited to such the configuration, but the display field
angle of the virtual image 300 may be changed between before and
after the movement of the drive lens 321.
For example when increasing the visual distance L0, the adjustment
unit 50 may change the size of the image 7 to make the display
field angle of the virtual image 300 smaller, contrary to the
increase of the visual distance L0. The adjustment unit 50 may
properly determine, based on the contents in the image 7, whether
or not the display field angle of the virtual image 300 should be
kept constant.
(3.3) Third Variation
In the basic example, the image producing unit 2 includes the
liquid crystal panel 21 (LCD) with the backlight, but is not
limited to the configuration including the LCD. As shown in FIG. 6,
the display device 4 may include an image producing unit 2A (Third
Variation). The image producing unit 2A may have an optical
diffusion transmissive type of screen 23 and an irradiation unit 24
that irradiates the screen 23 from a back side thereof with
light.
The irradiation unit 24 is a scanning-type optical irradiation
unit, and irradiates the screen 23 with light beam. Accordingly,
the image 7 (refer to FIG. 4B) is plotted on a display surface 230
that is a front surface or back surface of the screen 23 (herein
the front surface) by the light beam output from the irradiation
unit 24. The virtual image 300 is therefore formed in the target
space 400 by the light beam passing through the screen 23.
The irradiation unit 24 includes a light source 241 outputting
laser light, a scanning unit 242 performing scanning with the laser
light of the light source 241, and a lens 243. The light source 241
includes a laser module outputting the laser light. The scanning
unit 242 performs the scanning with the laser light of the light
source 241, thereby the light beam for scanning the display surface
230 being radiated to the screen 23. Herein the scanning unit 242
performs so-called Raster scan of scanning two-dimensionally with
respect to a longitudinal direction and a lateral direction of the
display surface 230. That is, the scanning unit 242 forms the
two-dimensional image by scanning with a beam spot formed on the
display surface 230. The scanning unit 242 includes, for example, a
fine scanning mirror using Micro Electro Mechanical Systems (MEMS).
That is, the scanning unit 242 includes an optical element (mirror
part) that reflects the laser light, and turns the optical element
to reflect the laser light of the light source 241 in a direction
in accordance with a turning angle (deflection angle) of the
optical element. Accordingly, the scanning unit 242 scans with the
laser light of the light source 241. The scanning unit 242 makes
the optical element turn around two axes (orthogonal to each other)
to realize the Raster scan of scanning two-dimensionally with the
laser light.
The display device 4 of the present variation includes a projection
unit 3A with a first mirror 33 and a second mirror 34. The first
mirror 33 and the second mirror 34 are arranged in that order on an
optical path of the light beam output from the image producing unit
2A. The first mirror 33 reflects the output light of the image
producing unit 2A toward the second mirror 34. The second mirror 34
reflects the output light reflected by the first mirror 33, of the
image producing unit 2A, toward the windshield 101. The first
mirror 33 is a convex mirror and the second mirror 34 is a concave
mirror.
In the present variation, the screen 23 is a target to be driven by
the drive unit 6. To change the visual distance L0, the controller
5 controls the drive unit 6 to drive the screen 23. Under the
control of the controller 5, the drive unit 6 moves the screen 23
to be closer to or more separated from the lens 243, thereby can
increasing or decreasing the visual distance L0 between the eye-box
800 and the virtual image 300.
The adjustment unit 50 of the controller 5 is configured to adjust
the brightness of the virtual image 300 (i.e., execute the
adjustment processing) according to the change in the visual
distance L0. The controller 5 changes, in accordance with the
driving quantity of the drive unit 6, both of the size of the image
7 to be displayed on the screen 23 and the optical quantity of the
light to be output from the light source 241.
Also in the present variation, the display system 1 can suppress
the reduction in the display quality and the visibility of the
virtual image 300 to be generated due to the change of the visual
distance L0.
(3.4) Fourth Variation
In the basic example, the adjustment unit 50 is provided in the
controller 5 of the display device 4. Optionally the adjustment
unit 50 may be however provided separately from the display device
4. For example as shown in FIG. 7, a control device 10 with the
adjustment unit 50 may be provided separately from a display device
4.
The display system 1 includes the display device 4 and the control
device 10. The display device 4 includes an image producing unit 2,
a projection unit 3, a drive unit 6, a controller 5 (having control
functions other than a function of the adjustment unit 50), a
detector X1, and a communication interface (capable of transmitting
and receiving signals to and from the control device 10). The
controller 5 of the display device 4 controls, when receiving from
the control device 10 a control signal for adjusting the luminance
of the virtual image 300, the image producing unit 2 in accordance
with the control signal. In this case, for example, the control
device 10 may be an Electronic Control Unit (ECU) installed in the
automobile 100, and the function of the adjustment unit 50 may be
provided in the ECU.
(3.5) Other Variations
For the image producing unit 2, an organic light emitting diode
(electroluminescence) panel may be used, for example.
Upon the change of the visual distance L0, the target to be driven
by the drive unit 6 may be for example a mirror or the liquid
crystal panel 21, instead of the drive lens 321 in the basic
example or the screen 23 in the Third Variation.
Also, the same function as that of the controller 5 (mainly the
adjustment unit 50) in the present disclosure may be implemented as
a computer program, or a non-transitory storage medium that stores
the computer program thereon, for example. The agent that
implements the adjustment unit 50 includes a computer system. The
computer system includes, as principal hardware components, a
processor and a memory. The function of the agent that implements
the adjustment unit 50 is performed by making the processor execute
the computer program stored in the memory of the computer system.
The computer program may be stored in advance in the memory of the
computer system. Alternatively, the computer program may also be
downloaded through a telecommunications line or be distributed
after having been stored in some computer-readable non-transitory
storage medium. Examples of the computer-readable non-transitory
storage media include a memory card, an optical disc, and a hard
disk drive. The processor of the computer system is made up of a
single or a plurality of electronic circuits including a
semiconductor integrated circuit (IC) or a largescale integrated
circuit (LSI). Those electronic circuits may be integrated together
on a single chip or distributed on multiple chips without
limitation. Those multiple chips may be integrated together in a
single device or distributed in multiple devices without
limitation.
Also the controller 5 in the basic example is implemented in a
single device, but not limited to such the configuration. For
example, at least some functions of the controller 5 may be
distributed in a plurality of devices. Similarly at least some
functions of the illuminance sensor X10, the amplifier X11 and the
A/D converter X12 of the detector X1 may be distributed in a
plurality of devices. Furthermore, at least some functions of the
controller 5 may be implemented as a cloud computing system as
well.
(4) Resume
As apparent from the foregoing description, a display system (1)
according to a first aspect includes an image producing unit (2,
2A), a projection unit (3, 3A) and an adjustment unit (50). The
image producing unit (2, 2A) has a display surface (210, 230) and
is configured to produce an image (7) on the display surface (210,
230). The projection unit (3, 3A) is configured to project a
virtual image (300) to a target space (400) with an output light of
the image producing unit (2, 2A). The virtual image (300)
corresponds to the image (7) produced by the image producing unit
(2, 2A). The display system (1) is configured to change a visual
distance (L0) between an eye-box (800) and the virtual image (300).
The adjustment unit (50) is configured to adjust brightness of the
virtual image (300) according to the visual distance (L0).
According to the first aspect, the display system (1) can suppress
a reduction in display quality and visibility of the virtual image
(300).
In a display system (1) according to a second aspect, which may be
implemented in conjunction with the first aspect, the adjustment
unit (50) is preferably further configured to adjust the brightness
of the virtual image (300) according to an ambient light
illuminance. According to the second aspect, the display system (1)
can more suppress the reduction in the display quality and
visibility of the virtual image (300).
In a display system (1) according to a third aspect, which may be
implemented in conjunction with the first aspect or the second
aspect, the adjustment unit (50) is preferably configured to change
a luminance of the display surface (210, 230) to adjust the
brightness of the virtual image (300). According to the third
aspect, the display system (1) can more suppress, with a simple
constitution, the reduction in the display quality and visibility
of the virtual image (300).
In a display system (1) according to a fourth aspect, which may be
implemented in conjunction with any one of the first to third
aspects, the adjustment unit (50) is preferably configured to
change lightness of colors of contents in the image (7) produced by
the image producing unit (2, 2A) to adjust the brightness of the
virtual image (300). According to the fourth aspect, the display
system (1) can more suppress, with a simple constitution, the
reduction in the display quality and visibility of the virtual
image (300).
In a display system (1) according to a fifth aspect, which may be
implemented in conjunction with any one of the first to fourth
aspects, the adjustment unit (50) is preferably configured to
increase the brightness of the virtual image (300), as the visual
distance (L0) is increased. According to the fifth aspect, the
display system (1) can suppress the reduction in the display
quality and visibility of the virtual image (300) (e.g., the
virtual image 300 is blurred and dimly seen) due to the increase in
the visual distance (L0).
In a display system (1) according to a sixth aspect, which may be
implemented in conjunction with any one of the first to fifth
aspects, a display field angle of the virtual image (300) projected
by the projection unit (3, 3A) is preferably constant, regardless
of a change in the visual distance (L0). According to the sixth
aspect, the display system (1) can reduce occurrence of a situation
that the an observer that observes the virtual image (300) feels
uncomfortable due to the increase in the display field angle of the
virtual image (300) together with the increase in the visual
distance (L0) for example. Note that "constant" mentioned herein is
not necessarily "strictly constant". The display field angle may be
substantially constant within a prescribed range including an
acceptable slight error.
In a display system (1) according to a seventh aspect, which may be
implemented in conjunction with the sixth aspect, the adjustment
unit (50) is preferably configured to adjust the brightness of the
virtual image (300) according to the visual distance (L0) so as to
make the brightness of the virtual image (300) fall within a
prescribed target range. According to the seventh aspect, the
display system (1) can suppress the brightness of the virtual image
(300) viewed from the observer from changing due to that the size
of the image (7) is changed to keep constant the display field
angle of the virtual image (300), for example.
In a display system (1) according to an eighth aspect, which may be
implemented in conjunction with any one of the first to seventh
aspects, the projection unit (3) preferably includes a zoom lens
(32) that is an optical element and allows the output light to pass
therethrough. The projection unit (3) is preferably configured to
modify a location of the zoom lens (32) to change the visual
distance (L0). According to the eighth aspect, the display system
(1) can realize the change of the visual distance (L0) with a
simple constitution.
In a display system (1) according to a ninth aspect, which may be
implemented in conjunction with any one of the first to eighth
aspects, the eye-box (800) is preferably a space region where eyes
of an observer that observes the virtual image (300) are
located.
In a display system (1) according to a tenth aspect, which may be
implemented in conjunction with any one of the first to ninth
aspects, the display system (1) is preferably applied to a movable
object (e.g., automobile 100). The target space (400) is a space in
front of a windshield (101) of the movable object.
In a display system (1) according to an eleventh aspect, which may
be implemented in conjunction with any one of the first to tenth
aspects, the adjustment unit (50) is preferably configured to
change display information of contents in the image (7) produced by
the image producing unit (2) to adjust the brightness of the
virtual image (300).
In a display system (1) according to a twelfth aspect, which may be
implemented in conjunction with any one of the first to eleventh
aspects, the image producing unit (2) preferably includes: a liquid
crystal panel (21), a front face of which constitutes the display
surface (210); and a light source device (22) serving as a
backlight for the liquid crystal panel (21). According to the
twelfth aspect, the display system (1) with the liquid crystal
panel (21) can suppress the reduction in the display quality and
visibility of the virtual image (300).
A control device (10) according to a thirteenth aspect includes the
adjustment unit (50) to be used for the display system (1) of any
one of the first to twelfth aspects. The control device (10) is
provided separately from a display device (4) including the image
producing unit (2, 2A) and the projection unit (3, 3A). According
to the thirteenth aspect, it is possible to provide the control
device (10), which can suppress the reduction in the display
quality and visibility of the virtual image (300).
A control method according to a fourteenth aspect is a control
method for a display system (1). The display system (1) includes an
image producing unit (2, 2A) and a projection unit (3, 3A). The
image producing unit (2, 2A) has a display surface (210, 230) and
is configured to produce an image (7) on the display surface (210,
230). The projection unit (3, 3A) is configured to project a
virtual image (300) to a target space (400) with an output light of
the image producing unit (2, 2A). The virtual image (300)
corresponds to the image (7) produced by the image producing unit
(2, 2A). The display system (1) is configured to change a visual
distance (L0) between an eye-box (800) and the virtual image (300).
The control method includes adjusting brightness of the virtual
image (300) according to the visual distance (L0). According to the
fourteenth aspect, it is possible to provide the control method,
which can suppress the reduction in the display quality and
visibility of the virtual image (300).
A computer program according to a fifteenth aspect causes a
computing system to perform the control method for the display
system (1) of the fourteenth aspect. According to the fifteenth
aspect, it is possible to provide a function, which can suppress
the reduction in the display quality and visibility of the virtual
image (300).
A non-transitory computer-readable medium according to a sixteenth
aspect has stored thereon a computer program which, upon execution
by a computing system, causes the computing system to perform a
control method for a display system (1). The display system (1)
includes an image producing unit (2, 2A) and a projection unit (3,
3A). The image producing unit (2, 2A) has a display surface (210,
230) and is configured to produce an image (7) on the display
surface (210, 230). The projection unit (3, 3A) is configured to
project a virtual image (300) to a target space (400) with an
output light of the image producing unit (2, 2A). The virtual image
(300) corresponds to the image (7) produced by the image producing
unit (2, 2A). The display system (1) is configured to change a
visual distance (L0) between an eye-box (800) and the virtual image
(300). The control method includes adjusting brightness of the
virtual image (300) according to the visual distance (L0).
A movable object (e.g., automobile 100) according to a seventeenth
aspect includes the display system (1) of any one of the first to
twelfth aspects and a reflective member (e.g., windshield 101)
configured to reflect light emitted from the projection unit (3,
3A). According to the seventeenth aspect, it is possible to provide
the movable object, which can suppress the reduction in the display
quality and visibility of the virtual image (300).
Since the configurations of the two to twelfth aspects are not
essential for the display system (1), any of the configurations may
be appropriately omitted.
While various embodiments have been described herein above, it is
to be appreciated that various changes in form and detail may be
made without departing from the spirit and scope of the present
disclosure presently or hereafter claimed.
The entire contents of Japanese Patent Application No. 2018-063909
mentioned above are incorporated by reference.
* * * * *